Ergonomically, a properly worn backpack is much safer than maneuvering an upright machine with the wrist. Visit www.cmmonline.com and search their library of articles on the subject of backpack vacuum and safety studies. You may also want to contact major manufacturers of backpack vacuums, as I believe they also have the data you seek.

Lastly, contact an occupational therapist, as the injuries from backpacks often occur from improper wearing of the machine ... — Perry S. Shimanoff, president of MC²